Polyfill of ES.next private name objects. This implementation patches ES5
Object methods where possible to emulate private names as much as possible.
Still in some cases private names can be discovered:

If Object methods from other JS contexts are used.

If properties are simply set like shown below, private names will be
revealed by for iteration:

object[secret]= value

It is recommended to use Object.defineProperty or
Object.defineProperties for defining private named properties. Those
methods will make sure to mark property as non-enumerable so that such
propertes won't be reavealed.